/*

 * jdmarker.c

 *

 * Copyright (C) 1991-1995, Thomas G. Lane.

 * This file is part of the Independent JPEG Group's software.

 * For conditions of distribution and use, see the accompanying README file.

 *

 * This file contains routines to decode JPEG datastream markers.

 * Most of the complexity arises from our desire to support input

 * suspension: if not all of the data for a marker is available,

 * we must exit back to the application.  On resumption, we reprocess

 * the marker.

 */



#define JPEG_INTERNALS

#include "jinclude.h"

#include "jpeglib.h"





typedef enum {			/* JPEG marker codes */

  M_SOF0  = 0xc0,

  M_SOF1  = 0xc1,

  M_SOF2  = 0xc2,

  M_SOF3  = 0xc3,

  

  M_SOF5  = 0xc5,

  M_SOF6  = 0xc6,

  M_SOF7  = 0xc7,

  

  M_JPG   = 0xc8,

  M_SOF9  = 0xc9,

  M_SOF10 = 0xca,

  M_SOF11 = 0xcb,

  

  M_SOF13 = 0xcd,

  M_SOF14 = 0xce,

  M_SOF15 = 0xcf,

  

  M_DHT   = 0xc4,

  

  M_DAC   = 0xcc,

  

  M_RST0  = 0xd0,

  M_RST1  = 0xd1,

  M_RST2  = 0xd2,

  M_RST3  = 0xd3,

  M_RST4  = 0xd4,

  M_RST5  = 0xd5,

  M_RST6  = 0xd6,

  M_RST7  = 0xd7,

  

  M_SOI   = 0xd8,

  M_EOI   = 0xd9,

  M_SOS   = 0xda,

  M_DQT   = 0xdb,

  M_DNL   = 0xdc,

  M_DRI   = 0xdd,

  M_DHP   = 0xde,

  M_EXP   = 0xdf,

  

  M_APP0  = 0xe0,

  M_APP1  = 0xe1,

  M_APP2  = 0xe2,

  M_APP3  = 0xe3,

  M_APP4  = 0xe4,

  M_APP5  = 0xe5,

  M_APP6  = 0xe6,

  M_APP7  = 0xe7,

  M_APP8  = 0xe8,

  M_APP9  = 0xe9,

  M_APP10 = 0xea,

  M_APP11 = 0xeb,

  M_APP12 = 0xec,

  M_APP13 = 0xed,

  M_APP14 = 0xee,

  M_APP15 = 0xef,

  

  M_JPG0  = 0xf0,

  M_JPG13 = 0xfd,

  M_COM   = 0xfe,

  

  M_TEM   = 0x01,

  

  M_ERROR = 0x100

} JPEG_MARKER;





/*

 * Macros for fetching data from the data source module.

 *

 * At all times, cinfo->src->next_input_byte and ->bytes_in_buffer reflect

 * the current restart point; we update them only when we have reached a

 * suitable place to restart if a suspension occurs.

 */



/* Declare and initialize local copies of input pointer/count */

#define INPUT_VARS(cinfo)  \

	struct jpeg_source_mgr * datasrc = (cinfo)->src;  \

	const JOCTET * next_input_byte = datasrc->next_input_byte;  \

	size_t bytes_in_buffer = datasrc->bytes_in_buffer



/* Unload the local copies --- do this only at a restart boundary */

#define INPUT_SYNC(cinfo)  \

	( datasrc->next_input_byte = next_input_byte,  \

	  datasrc->bytes_in_buffer = bytes_in_buffer )



/* Reload the local copies --- seldom used except in MAKE_BYTE_AVAIL */

#define INPUT_RELOAD(cinfo)  \

	( next_input_byte = datasrc->next_input_byte,  \

	  bytes_in_buffer = datasrc->bytes_in_buffer )



/* Internal macro for INPUT_BYTE and INPUT_2BYTES: make a byte available.

 * Note we do *not* do INPUT_SYNC before calling fill_input_buffer,

 * but we must reload the local copies after a successful fill.

 */

#define MAKE_BYTE_AVAIL(cinfo,action)  \

	if (bytes_in_buffer == 0) {  \

	  if (! (*datasrc->fill_input_buffer) (cinfo))  \

	    { action; }  \

	  INPUT_RELOAD(cinfo);  \

	}  \

	bytes_in_buffer--



/* Read a byte into variable V.

 * If must suspend, take the specified action (typically "return FALSE").

 */

#define INPUT_BYTE(cinfo,V,action)  \

	MAKESTMT( MAKE_BYTE_AVAIL(cinfo,action); \

		  V = GETJOCTET(*next_input_byte++); )



/* As above, but read two bytes interpreted as an unsigned 16-bit integer.

 * V should be declared unsigned int or perhaps INT32.

 */

#define INPUT_2BYTES(cinfo,V,action)  \

	MAKESTMT( MAKE_BYTE_AVAIL(cinfo,action); \

		  V = ((unsigned int) GETJOCTET(*next_input_byte++)) << 8; \

		  MAKE_BYTE_AVAIL(cinfo,action); \

		  V += GETJOCTET(*next_input_byte++); )





/*

 * Routines to process JPEG markers.

 *

 * Entry condition: JPEG marker itself has been read and its code saved

 *   in cinfo->unread_marker; input restart point is just after the marker.

 *

 * Exit: if return TRUE, have read and processed any parameters, and have

 *   updated the restart point to point after the parameters.

 *   If return FALSE, was forced to suspend before reaching end of

 *   marker parameters; restart point has not been moved.  Same routine

 *   will be called again after application supplies more input data.

 *

 * This approach to suspension assumes that all of a marker's parameters can

 * fit into a single input bufferload.  This should hold for "normal"

 * markers.  Some COM/APPn markers might have large parameter segments,

 * but we use skip_input_data to get past those, and thereby put the problem

 * on the source manager's shoulders.

 *

 * Note that we don't bother to avoid duplicate trace messages if a

 * suspension occurs within marker parameters.  Other side effects

 * require more care.

 */





LOCAL boolean

get_soi (j_decompress_ptr cinfo)

/* Process an SOI marker */

{

  int i;

  

  TRACEMS(cinfo, 1, JTRC_SOI);



  if (cinfo->marker->saw_SOI)

    ERREXIT(cinfo, JERR_SOI_DUPLICATE);



  /* Reset all parameters that are defined to be reset by SOI */



  for (i = 0; i < NUM_ARITH_TBLS; i++) {

    cinfo->arith_dc_L[i] = 0;

    cinfo->arith_dc_U[i] = 1;

    cinfo->arith_ac_K[i] = 5;

  }

  cinfo->restart_interval = 0;



  /* Set initial assumptions for colorspace etc */



  cinfo->jpeg_color_space = JCS_UNKNOWN;

  cinfo->CCIR601_sampling = FALSE; /* Assume non-CCIR sampling??? */



  cinfo->saw_JFIF_marker = FALSE;

  cinfo->density_unit = 0;	/* set default JFIF APP0 values */

  cinfo->X_density = 1;

  cinfo->Y_density = 1;

  cinfo->saw_Adobe_marker = FALSE;

  cinfo->Adobe_transform = 0;



  cinfo->marker->saw_SOI = TRUE;



  return TRUE;

}





LOCAL boolean

get_sof (j_decompress_ptr cinfo, boolean is_prog, boolean is_arith)

/* Process a SOFn marker */

{

  INT32 length;

  int c, ci;

  jpeg_component_info * compptr;

  INPUT_VARS(cinfo);



  cinfo->progressive_mode = is_prog;

  cinfo->arith_code = is_arith;



  INPUT_2BYTES(cinfo, length, return FALSE);



  INPUT_BYTE(cinfo, cinfo->data_precision, return FALSE);

  INPUT_2BYTES(cinfo, cinfo->image_height, return FALSE);

  INPUT_2BYTES(cinfo, cinfo->image_width, return FALSE);

  INPUT_BYTE(cinfo, cinfo->num_components, return FALSE);



  length -= 8;



  TRACEMS4(cinfo, 1, JTRC_SOF, cinfo->unread_marker,

	   (int) cinfo->image_width, (int) cinfo->image_height,

	   cinfo->num_components);



  if (cinfo->marker->saw_SOF)

    ERREXIT(cinfo, JERR_SOF_DUPLICATE);



  /* We don't support files in which the image height is initially specified */

  /* as 0 and is later redefined by DNL.  As long as we have to check that,  */

  /* might as well have a general sanity check. */

  if (cinfo->image_height <= 0 || cinfo->image_width <= 0

      || cinfo->num_components <= 0)

    ERREXIT(cinfo, JERR_EMPTY_IMAGE);



  if (length != (cinfo->num_components * 3))

    ERREXIT(cinfo, JERR_BAD_LENGTH);



  if (cinfo->comp_info == NULL)	/* do only once, even if suspend */

    cinfo->comp_info = (jpeg_component_info *) (*cinfo->mem->alloc_small)

			((j_common_ptr) cinfo, JPOOL_IMAGE,

			 cinfo->num_components * SIZEOF(jpeg_component_info));

  

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

       ci++, compptr++) {

    compptr->component_index = ci;

    INPUT_BYTE(cinfo, compptr->component_id, return FALSE);

    INPUT_BYTE(cinfo, c, return FALSE);

    compptr->h_samp_factor = (c >> 4) & 15;

    compptr->v_samp_factor = (c     ) & 15;

    INPUT_BYTE(cinfo, compptr->quant_tbl_no, return FALSE);



    TRACEMS4(cinfo, 1, JTRC_SOF_COMPONENT,

	     compptr->component_id, compptr->h_samp_factor,

	     compptr->v_samp_factor, compptr->quant_tbl_no);

  }



  cinfo->marker->saw_SOF = TRUE;



  INPUT_SYNC(cinfo);

  return TRUE;

}





LOCAL boolean

get_sos (j_decompress_ptr cinfo)

/* Process a SOS marker */

{

  INT32 length;

  int i, ci, n, c, cc;

  jpeg_component_info * compptr;

  INPUT_VARS(cinfo);



  if (! cinfo->marker->saw_SOF)

    ERREXIT(cinfo, JERR_SOS_NO_SOF);



  INPUT_2BYTES(cinfo, length, return FALSE);



  INPUT_BYTE(cinfo, n, return FALSE); /* Number of components */



  if (length != (n * 2 + 6) || n < 1 || n > MAX_COMPS_IN_SCAN)

    ERREXIT(cinfo, JERR_BAD_LENGTH);



  TRACEMS1(cinfo, 1, JTRC_SOS, n);



  cinfo->comps_in_scan = n;



  /* Collect the component-spec parameters */



  for (i = 0; i < n; i++) {

    INPUT_BYTE(cinfo, cc, return FALSE);

    INPUT_BYTE(cinfo, c, return FALSE);

    

    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

	 ci++, compptr++) {

      if (cc == compptr->component_id)

	goto id_found;

    }



    ERREXIT1(cinfo, JERR_BAD_COMPONENT_ID, cc);



  id_found:



    cinfo->cur_comp_info[i] = compptr;

    compptr->dc_tbl_no = (c >> 4) & 15;

    compptr->ac_tbl_no = (c     ) & 15;

    

    TRACEMS3(cinfo, 1, JTRC_SOS_COMPONENT, cc,

	     compptr->dc_tbl_no, compptr->ac_tbl_no);

  }



  /* Collect the additional scan parameters Ss, Se, Ah/Al. */

  INPUT_BYTE(cinfo, c, return FALSE);

  cinfo->Ss = c;

  INPUT_BYTE(cinfo, c, return FALSE);

  cinfo->Se = c;

  INPUT_BYTE(cinfo, c, return FALSE);

  cinfo->Ah = (c >> 4) & 15;

  cinfo->Al = (c     ) & 15;



  TRACEMS4(cinfo, 1, JTRC_SOS_PARAMS, cinfo->Ss, cinfo->Se,

	   cinfo->Ah, cinfo->Al);



  /* Prepare to scan data & restart markers */

  cinfo->marker->next_restart_num = 0;



  /* Count another SOS marker */

  cinfo->input_scan_number++;



  INPUT_SYNC(cinfo);

  return TRUE;

}





METHODDEF boolean

get_app0 (j_decompress_ptr cinfo)

/* Process an APP0 marker */

{

#define JFIF_LEN 14

  INT32 length;

  UINT8 b[JFIF_LEN];

  int buffp;

  INPUT_VARS(cinfo);



  INPUT_2BYTES(cinfo, length, return FALSE);

  length -= 2;



  /* See if a JFIF APP0 marker is present */



  if (length >= JFIF_LEN) {

    for (buffp = 0; buffp < JFIF_LEN; buffp++)

      INPUT_BYTE(cinfo, b[buffp], return FALSE);

    length -= JFIF_LEN;



    if (b[0]==0x4A && b[1]==0x46 && b[2]==0x49 && b[3]==0x46 && b[4]==0) {

      /* Found JFIF APP0 marker: check version */

      /* Major version must be 1, anything else signals an incompatible change.

       * We used to treat this as an error, but now it's a nonfatal warning,

       * because some bozo at Hijaak couldn't read the spec.

       * Minor version should be 0..2, but process anyway if newer.

       */

      if (b[5] != 1)

	WARNMS2(cinfo, JWRN_JFIF_MAJOR, b[5], b[6]);

      else if (b[6] > 2)

	TRACEMS2(cinfo, 1, JTRC_JFIF_MINOR, b[5], b[6]);

      /* Save info */

      cinfo->saw_JFIF_marker = TRUE;

      cinfo->density_unit = b[7];

      cinfo->X_density = (b[8] << 8) + b[9];

      cinfo->Y_density = (b[10] << 8) + b[11];

      TRACEMS3(cinfo, 1, JTRC_JFIF,

	       cinfo->X_density, cinfo->Y_density, cinfo->density_unit);

      if (b[12] | b[13])

	TRACEMS2(cinfo, 1, JTRC_JFIF_THUMBNAIL, b[12], b[13]);

      if (length != ((INT32) b[12] * (INT32) b[13] * (INT32) 3))

	TRACEMS1(cinfo, 1, JTRC_JFIF_BADTHUMBNAILSIZE, (int) length);

    } else {

      /* Start of APP0 does not match "JFIF" */

      TRACEMS1(cinfo, 1, JTRC_APP0, (int) length + JFIF_LEN);

    }

  } else {

    /* Too short to be JFIF marker */

    TRACEMS1(cinfo, 1, JTRC_APP0, (int) length);

  }



  INPUT_SYNC(cinfo);

  if (length > 0)		/* skip any remaining data -- could be lots */

    (*cinfo->src->skip_input_data) (cinfo, (long) length);



  return TRUE;

}





METHODDEF boolean

get_app14 (j_decompress_ptr cinfo)

/* Process an APP14 marker */

{

#define ADOBE_LEN 12

  INT32 length;

  UINT8 b[ADOBE_LEN];

  int buffp;

  unsigned int version, flags0, flags1, transform;

  INPUT_VARS(cinfo);



  INPUT_2BYTES(cinfo, length, return FALSE);

  length -= 2;



  /* See if an Adobe APP14 marker is present */



  if (length >= ADOBE_LEN) {

    for (buffp = 0; buffp < ADOBE_LEN; buffp++)

      INPUT_BYTE(cinfo, b[buffp], return FALSE);

    length -= ADOBE_LEN;



    if (b[0]==0x41 && b[1]==0x64 && b[2]==0x6F && b[3]==0x62 && b[4]==0x65) {

      /* Found Adobe APP14 marker */

      version = (b[5] << 8) + b[6];

      flags0 = (b[7] << 8) + b[8];

      flags1 = (b[9] << 8) + b[10];

      transform = b[11];

      TRACEMS4(cinfo, 1, JTRC_ADOBE, version, flags0, flags1, transform);

      cinfo->saw_Adobe_marker = TRUE;

      cinfo->Adobe_transform = (UINT8) transform;

    } else {

      /* Start of APP14 does not match "Adobe" */

      TRACEMS1(cinfo, 1, JTRC_APP14, (int) length + ADOBE_LEN);

    }

  } else {

    /* Too short to be Adobe marker */

    TRACEMS1(cinfo, 1, JTRC_APP14, (int) length);

  }



  INPUT_SYNC(cinfo);

  if (length > 0)		/* skip any remaining data -- could be lots */

    (*cinfo->src->skip_input_data) (cinfo, (long) length);



  return TRUE;

}





LOCAL boolean

get_dac (j_decompress_ptr cinfo)

/* Process a DAC marker */

{

  INT32 length;

  int index, val;

  INPUT_VARS(cinfo);



  INPUT_2BYTES(cinfo, length, return FALSE);

  length -= 2;

  

  while (length > 0) {

    INPUT_BYTE(cinfo, index, return FALSE);

    INPUT_BYTE(cinfo, val, return FALSE);



    length -= 2;



    TRACEMS2(cinfo, 1, JTRC_DAC, index, val);



    if (index < 0 || index >= (2*NUM_ARITH_TBLS))

      ERREXIT1(cinfo, JERR_DAC_INDEX, index);



    if (index >= NUM_ARITH_TBLS) { /* define AC table */

      cinfo->arith_ac_K[index-NUM_ARITH_TBLS] = (UINT8) val;

    } else {			/* define DC table */

      cinfo->arith_dc_L[index] = (UINT8) (val & 0x0F);

      cinfo->arith_dc_U[index] = (UINT8) (val >> 4);

      if (cinfo->arith_dc_L[index] > cinfo->arith_dc_U[index])

	ERREXIT1(cinfo, JERR_DAC_VALUE, val);

    }

  }



  INPUT_SYNC(cinfo);

  return TRUE;

}





LOCAL boolean

get_dht (j_decompress_ptr cinfo)

/* Process a DHT marker */

{

  INT32 length;

  UINT8 bits[17];

  UINT8 huffval[256];

  int i, index, count;

  JHUFF_TBL **htblptr;

  INPUT_VARS(cinfo);



  INPUT_2BYTES(cinfo, length, return FALSE);

  length -= 2;

  

  while (length > 0) {

    INPUT_BYTE(cinfo, index, return FALSE);



    TRACEMS1(cinfo, 1, JTRC_DHT, index);

      

    bits[0] = 0;

    count = 0;

    for (i = 1; i <= 16; i++) {

      INPUT_BYTE(cinfo, bits[i], return FALSE);

      count += bits[i];

    }



    length -= 1 + 16;



    TRACEMS8(cinfo, 2, JTRC_HUFFBITS,

	     bits[1], bits[2], bits[3], bits[4],

	     bits[5], bits[6], bits[7], bits[8]);

    TRACEMS8(cinfo, 2, JTRC_HUFFBITS,

	     bits[9], bits[10], bits[11], bits[12],

	     bits[13], bits[14], bits[15], bits[16]);



    if (count > 256 || ((INT32) count) > length)

      ERREXIT(cinfo, JERR_DHT_COUNTS);



    for (i = 0; i < count; i++)

      INPUT_BYTE(cinfo, huffval[i], return FALSE);



    length -= count;



    if (index & 0x10) {		/* AC table definition */

      index -= 0x10;

      htblptr = &cinfo->ac_huff_tbl_ptrs[index];

    } else {			/* DC table definition */

      htblptr = &cinfo->dc_huff_tbl_ptrs[index];

    }



    if (index < 0 || index >= NUM_HUFF_TBLS)

      ERREXIT1(cinfo, JERR_DHT_INDEX, index);



    if (*htblptr == NULL)

      *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);

  

    MEMCOPY((*htblptr)->bits, bits, SIZEOF((*htblptr)->bits));

    MEMCOPY((*htblptr)->huffval, huffval, SIZEOF((*htblptr)->huffval));

  }



  INPUT_SYNC(cinfo);

  return TRUE;

}





LOCAL boolean

get_dqt (j_decompress_ptr cinfo)

/* Process a DQT marker */

{

  INT32 length;

  int n, i, prec;

  unsigned int tmp;

  JQUANT_TBL *quant_ptr;

  INPUT_VARS(cinfo);



  INPUT_2BYTES(cinfo, length, return FALSE);

  length -= 2;



  while (length > 0) {

    INPUT_BYTE(cinfo, n, return FALSE);

    prec = n >> 4;

    n &= 0x0F;



    TRACEMS2(cinfo, 1, JTRC_DQT, n, prec);



    if (n >= NUM_QUANT_TBLS)

      ERREXIT1(cinfo, JERR_DQT_INDEX, n);

      

    if (cinfo->quant_tbl_ptrs[n] == NULL)

      cinfo->quant_tbl_ptrs[n] = jpeg_alloc_quant_table((j_common_ptr) cinfo);

    quant_ptr = cinfo->quant_tbl_ptrs[n];



    for (i = 0; i < DCTSIZE2; i++) {

      if (prec)

	INPUT_2BYTES(cinfo, tmp, return FALSE);

      else

	INPUT_BYTE(cinfo, tmp, return FALSE);

      quant_ptr->quantval[i] = (UINT16) tmp;

    }



    for (i = 0; i < DCTSIZE2; i += 8) {

      TRACEMS8(cinfo, 2, JTRC_QUANTVALS,

	       quant_ptr->quantval[i  ], quant_ptr->quantval[i+1],

	       quant_ptr->quantval[i+2], quant_ptr->quantval[i+3],

	       quant_ptr->quantval[i+4], quant_ptr->quantval[i+5],

	       quant_ptr->quantval[i+6], quant_ptr->quantval[i+7]);

    }



    length -= DCTSIZE2+1;

    if (prec) length -= DCTSIZE2;

  }



  INPUT_SYNC(cinfo);

  return TRUE;

}





LOCAL boolean

get_dri (j_decompress_ptr cinfo)

/* Process a DRI marker */

{

  INT32 length;

  unsigned int tmp;

  INPUT_VARS(cinfo);



  INPUT_2BYTES(cinfo, length, return FALSE);

  

  if (length != 4)

    ERREXIT(cinfo, JERR_BAD_LENGTH);



  INPUT_2BYTES(cinfo, tmp, return FALSE);



  TRACEMS1(cinfo, 1, JTRC_DRI, tmp);



  cinfo->restart_interval = tmp;



  INPUT_SYNC(cinfo);

  return TRUE;

}





METHODDEF boolean

skip_variable (j_decompress_ptr cinfo)

/* Skip over an unknown or uninteresting variable-length marker */

{

  INT32 length;

  INPUT_VARS(cinfo);



  INPUT_2BYTES(cinfo, length, return FALSE);

  

  TRACEMS2(cinfo, 1, JTRC_MISC_MARKER, cinfo->unread_marker, (int) length);



  INPUT_SYNC(cinfo);		/* do before skip_input_data */

  (*cinfo->src->skip_input_data) (cinfo, (long) length - 2L);



  return TRUE;

}





/*

 * Find the next JPEG marker, save it in cinfo->unread_marker.

 * Returns FALSE if had to suspend before reaching a marker;

 * in that case cinfo->unread_marker is unchanged.

 *

 * Note that the result might not be a valid marker code,

 * but it will never be 0 or FF.

 */



LOCAL boolean

next_marker (j_decompress_ptr cinfo)

{

  int c;

  INPUT_VARS(cinfo);



  for (;;) {

    INPUT_BYTE(cinfo, c, return FALSE);

    /* Skip any non-FF bytes.

     * This may look a bit inefficient, but it will not occur in a valid file.

     * We sync after each discarded byte so that a suspending data source

     * can discard the byte from its buffer.

     */

    while (c != 0xFF) {

      cinfo->marker->discarded_bytes++;

      INPUT_SYNC(cinfo);

      INPUT_BYTE(cinfo, c, return FALSE);

    }

    /* This loop swallows any duplicate FF bytes.  Extra FFs are legal as

     * pad bytes, so don't count them in discarded_bytes.  We assume there

     * will not be so many consecutive FF bytes as to overflow a suspending

     * data source's input buffer.

     */

    do {

      INPUT_BYTE(cinfo, c, return FALSE);

    } while (c == 0xFF);

    if (c != 0)

      break;			/* found a valid marker, exit loop */

    /* Reach here if we found a stuffed-zero data sequence (FF/00).

     * Discard it and loop back to try again.

     */

    cinfo->marker->discarded_bytes += 2;

    INPUT_SYNC(cinfo);

  }



  if (cinfo->marker->discarded_bytes != 0) {

    WARNMS2(cinfo, JWRN_EXTRANEOUS_DATA, cinfo->marker->discarded_bytes, c);

    cinfo->marker->discarded_bytes = 0;

  }



  cinfo->unread_marker = c;



  INPUT_SYNC(cinfo);

  return TRUE;

}





LOCAL boolean

first_marker (j_decompress_ptr cinfo)

/* Like next_marker, but used to obtain the initial SOI marker. */

/* For this marker, we do not allow preceding garbage or fill; otherwise,

 * we might well scan an entire input file before realizing it ain't JPEG.

 * If an application wants to process non-JFIF files, it must seek to the

 * SOI before calling the JPEG library.

 */

{

  int c, c2;

  INPUT_VARS(cinfo);



  INPUT_BYTE(cinfo, c, return FALSE);

  INPUT_BYTE(cinfo, c2, return FALSE);

  if (c != 0xFF || c2 != (int) M_SOI)

    ERREXIT2(cinfo, JERR_NO_SOI, c, c2);



  cinfo->unread_marker = c2;



  INPUT_SYNC(cinfo);

  return TRUE;

}





/*

 * Read markers until SOS or EOI.

 *

 * Returns same codes as are defined for jpeg_consume_input:

 * JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.

 */



METHODDEF int

read_markers (j_decompress_ptr cinfo)

{

  /* Outer loop repeats once for each marker. */

  for (;;) {

    /* Collect the marker proper, unless we already did. */

    /* NB: first_marker() enforces the requirement that SOI appear first. */

    if (cinfo->unread_marker == 0) {

      if (! cinfo->marker->saw_SOI) {

	if (! first_marker(cinfo))

	  return JPEG_SUSPENDED;

      } else {

	if (! next_marker(cinfo))

	  return JPEG_SUSPENDED;

      }

    }

    /* At this point cinfo->unread_marker contains the marker code and the

     * input point is just past the marker proper, but before any parameters.

     * A suspension will cause us to return with this state still true.

     */

    switch (cinfo->unread_marker) {

    case M_SOI:

      if (! get_soi(cinfo))

	return JPEG_SUSPENDED;

      break;



    case M_SOF0:		/* Baseline */

    case M_SOF1:		/* Extended sequential, Huffman */

      if (! get_sof(cinfo, FALSE, FALSE))

	return JPEG_SUSPENDED;

      break;



    case M_SOF2:		/* Progressive, Huffman */

      if (! get_sof(cinfo, TRUE, FALSE))

	return JPEG_SUSPENDED;

      break;



    case M_SOF9:		/* Extended sequential, arithmetic */

      if (! get_sof(cinfo, FALSE, TRUE))

	return JPEG_SUSPENDED;

      break;



    case M_SOF10:		/* Progressive, arithmetic */

      if (! get_sof(cinfo, TRUE, TRUE))

	return JPEG_SUSPENDED;

      break;



    /* Currently unsupported SOFn types */

    case M_SOF3:		/* Lossless, Huffman */

    case M_SOF5:		/* Differential sequential, Huffman */

    case M_SOF6:		/* Differential progressive, Huffman */

    case M_SOF7:		/* Differential lossless, Huffman */

    case M_JPG:			/* Reserved for JPEG extensions */

    case M_SOF11:		/* Lossless, arithmetic */

    case M_SOF13:		/* Differential sequential, arithmetic */

    case M_SOF14:		/* Differential progressive, arithmetic */

    case M_SOF15:		/* Differential lossless, arithmetic */

      ERREXIT1(cinfo, JERR_SOF_UNSUPPORTED, cinfo->unread_marker);

      break;



    case M_SOS:

      if (! get_sos(cinfo))

	return JPEG_SUSPENDED;

      cinfo->unread_marker = 0;	/* processed the marker */

      return JPEG_REACHED_SOS;

    

    case M_EOI:

      TRACEMS(cinfo, 1, JTRC_EOI);

      cinfo->unread_marker = 0;	/* processed the marker */

      return JPEG_REACHED_EOI;

      

    case M_DAC:

      if (! get_dac(cinfo))

	return JPEG_SUSPENDED;

      break;

      

    case M_DHT:

      if (! get_dht(cinfo))

	return JPEG_SUSPENDED;

      break;

      

    case M_DQT:

      if (! get_dqt(cinfo))

	return JPEG_SUSPENDED;

      break;

      

    case M_DRI:

      if (! get_dri(cinfo))

	return JPEG_SUSPENDED;

      break;

      

    case M_APP0:

    case M_APP1:

    case M_APP2:

    case M_APP3:

    case M_APP4:

    case M_APP5:

    case M_APP6:

    case M_APP7:

    case M_APP8:

    case M_APP9:

    case M_APP10:

    case M_APP11:

    case M_APP12:

    case M_APP13:

    case M_APP14:

    case M_APP15:

      if (! (*cinfo->marker->process_APPn[cinfo->unread_marker - (int) M_APP0]) (cinfo))

	return JPEG_SUSPENDED;

      break;

      

    case M_COM:

      if (! (*cinfo->marker->process_COM) (cinfo))

	return JPEG_SUSPENDED;

      break;



    case M_RST0:		/* these are all parameterless */

    case M_RST1:

    case M_RST2:

    case M_RST3:

    case M_RST4:

    case M_RST5:

    case M_RST6:

    case M_RST7:

    case M_TEM:

      TRACEMS1(cinfo, 1, JTRC_PARMLESS_MARKER, cinfo->unread_marker);

      break;



    case M_DNL:			/* Ignore DNL ... perhaps the wrong thing */

      if (! skip_variable(cinfo))

	return JPEG_SUSPENDED;

      break;



    default:			/* must be DHP, EXP, JPGn, or RESn */

      /* For now, we treat the reserved markers as fatal errors since they are

       * likely to be used to signal incompatible JPEG Part 3 extensions.

       * Once the JPEG 3 version-number marker is well defined, this code

       * ought to change!

       */

      ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker);

      break;

    }

    /* Successfully processed marker, so reset state variable */

    cinfo->unread_marker = 0;

  } /* end loop */

}





/*

 * Read a restart marker, which is expected to appear next in the datastream;

 * if the marker is not there, take appropriate recovery action.

 * Returns FALSE if suspension is required.

 *

 * This is called by the entropy decoder after it has read an appropriate

 * number of MCUs.  cinfo->unread_marker may be nonzero if the entropy decoder

 * has already read a marker from the data source.  Under normal conditions

 * cinfo->unread_marker will be reset to 0 before returning; if not reset,

 * it holds a marker which the decoder will be unable to read past.

 */



METHODDEF boolean

read_restart_marker (j_decompress_ptr cinfo)

{

  /* Obtain a marker unless we already did. */

  /* Note that next_marker will complain if it skips any data. */

  if (cinfo->unread_marker == 0) {

    if (! next_marker(cinfo))

      return FALSE;

  }



  if (cinfo->unread_marker ==

      ((int) M_RST0 + cinfo->marker->next_restart_num)) {

    /* Normal case --- swallow the marker and let entropy decoder continue */

    TRACEMS1(cinfo, 2, JTRC_RST, cinfo->marker->next_restart_num);

    cinfo->unread_marker = 0;

  } else {

    /* Uh-oh, the restart markers have been messed up. */

    /* Let the data source manager determine how to resync. */

    if (! (*cinfo->src->resync_to_restart) (cinfo,

					    cinfo->marker->next_restart_num))

      return FALSE;

  }



  /* Update next-restart state */

  cinfo->marker->next_restart_num = (cinfo->marker->next_restart_num + 1) & 7;



  return TRUE;

}





/*

 * This is the default resync_to_restart method for data source managers

 * to use if they don't have any better approach.  Some data source managers

 * may be able to back up, or may have additional knowledge about the data

 * which permits a more intelligent recovery strategy; such managers would

 * presumably supply their own resync method.

 *

 * read_restart_marker calls resync_to_restart if it finds a marker other than

 * the restart marker it was expecting.  (This code is *not* used unless

 * a nonzero restart interval has been declared.)  cinfo->unread_marker is

 * the marker code actually found (might be anything, except 0 or FF).

 * The desired restart marker number (0..7) is passed as a parameter.

 * This routine is supposed to apply whatever error recovery strategy seems

 * appropriate in order to position the input stream to the next data segment.

 * Note that cinfo->unread_marker is treated as a marker appearing before

 * the current data-source input point; usually it should be reset to zero

 * before returning.

 * Returns FALSE if suspension is required.

 *

 * This implementation is substantially constrained by wanting to treat the

 * input as a data stream; this means we can't back up.  Therefore, we have

 * only the following actions to work with:

 *   1. Simply discard the marker and let the entropy decoder resume at next

 *      byte of file.

 *   2. Read forward until we find another marker, discarding intervening

 *      data.  (In theory we could look ahead within the current bufferload,

 *      without having to discard data if we don't find the desired marker.

 *      This idea is not implemented here, in part because it makes behavior

 *      dependent on buffer size and chance buffer-boundary positions.)

 *   3. Leave the marker unread (by failing to zero cinfo->unread_marker).

 *      This will cause the entropy decoder to process an empty data segment,

 *      inserting dummy zeroes, and then we will reprocess the marker.

 *

 * #2 is appropriate if we think the desired marker lies ahead, while #3 is

 * appropriate if the found marker is a future restart marker (indicating

 * that we have missed the desired restart marker, probably because it got

 * corrupted).

 * We apply #2 or #3 if the found marker is a restart marker no more than

 * two counts behind or ahead of the expected one.  We also apply #2 if the

 * found marker is not a legal JPEG marker code (it's certainly bogus data).

 * If the found marker is a restart marker more than 2 counts away, we do #1

 * (too much risk that the marker is erroneous; with luck we will be able to

 * resync at some future point).

 * For any valid non-restart JPEG marker, we apply #3.  This keeps us from

 * overrunning the end of a scan.  An implementation limited to single-scan

 * files might find it better to apply #2 for markers other than EOI, since

 * any other marker would have to be bogus data in that case.

 */



GLOBAL boolean

jpeg_resync_to_restart (j_decompress_ptr cinfo, int desired)

{

  int marker = cinfo->unread_marker;

  int action = 1;

  

  /* Always put up a warning. */

  WARNMS2(cinfo, JWRN_MUST_RESYNC, marker, desired);

  

  /* Outer loop handles repeated decision after scanning forward. */

  for (;;) {

    if (marker < (int) M_SOF0)

      action = 2;		/* invalid marker */

    else if (marker < (int) M_RST0 || marker > (int) M_RST7)

      action = 3;		/* valid non-restart marker */

    else {

      if (marker == ((int) M_RST0 + ((desired+1) & 7)) ||

	  marker == ((int) M_RST0 + ((desired+2) & 7)))

	action = 3;		/* one of the next two expected restarts */

      else if (marker == ((int) M_RST0 + ((desired-1) & 7)) ||

	       marker == ((int) M_RST0 + ((desired-2) & 7)))

	action = 2;		/* a prior restart, so advance */

      else

	action = 1;		/* desired restart or too far away */

    }

    TRACEMS2(cinfo, 4, JTRC_RECOVERY_ACTION, marker, action);

    switch (action) {

    case 1:

      /* Discard marker and let entropy decoder resume processing. */

      cinfo->unread_marker = 0;

      return TRUE;

    case 2:

      /* Scan to the next marker, and repeat the decision loop. */

      if (! next_marker(cinfo))

	return FALSE;

      marker = cinfo->unread_marker;

      break;

    case 3:

      /* Return without advancing past this marker. */

      /* Entropy decoder will be forced to process an empty segment. */

      return TRUE;

    }

  } /* end loop */

}





/*

 * Reset marker processing state to begin a fresh datastream.

 */



METHODDEF void

reset_marker_reader (j_decompress_ptr cinfo)

{

  cinfo->comp_info = NULL;		/* until allocated by get_sof */

  cinfo->input_scan_number = 0;		/* no SOS seen yet */

  cinfo->unread_marker = 0;		/* no pending marker */

  cinfo->marker->saw_SOI = FALSE;	/* set internal state too */

  cinfo->marker->saw_SOF = FALSE;

  cinfo->marker->discarded_bytes = 0;

}





/*

 * Initialize the marker reader module.

 * This is called only once, when the decompression object is created.

 */



GLOBAL void

jinit_marker_reader (j_decompress_ptr cinfo)

{

  int i;



  /* Create subobject in permanent pool */

  cinfo->marker = (struct jpeg_marker_reader *)

    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,

				SIZEOF(struct jpeg_marker_reader));

  /* Initialize method pointers */

  cinfo->marker->reset_marker_reader = reset_marker_reader;

  cinfo->marker->read_markers = read_markers;

  cinfo->marker->read_restart_marker = read_restart_marker;

  cinfo->marker->process_COM = skip_variable;

  for (i = 0; i < 16; i++)

    cinfo->marker->process_APPn[i] = skip_variable;

  cinfo->marker->process_APPn[0] = get_app0;

  cinfo->marker->process_APPn[14] = get_app14;

  /* Reset marker processing state */

  reset_marker_reader(cinfo);

}

